C: My current system partition
Y: An empty disk I was using to backup Z
Z: The system partition from an old system (that I had in my new system in order to transfer files)

After having filled up Y: in the process of trying to backup Z:, I deleted some extraneous files from Z.

I loaded up PathSync v0.4 beta and set Z: as my local drive and Y: as remote. I then used "Local>Remote" mode with the intention that it would delete the files I had removed from Z: on Y:.

Well, next thing I know, my C: drive (which had less than 50GB of free space before) had over 200GB of free space... BUT THE C DRIVE WASN'T SPECIFIED IN PATHSYNC AT ALL. I looked at it both before and after the backup and the drive letters were set to Z: (local) and Y: (remote).

Anybody know what happened? This is... frustrating and unexpected.

I honestly don't know what happened. The only thing I could come up with was that maybe PathSync got confused by junction links or symbolic links or something?

I'm off to buy StorageCraft's ShadowProtect Desktop, since I'd luckily done a backup of the C partition yesterday using the 30-day SPD trial.